Substance for indicating the exhaustion of gas purifying masses and alpha method of using the same



Patented Sept. 5, 1933 SUBSTANCE FOR INDICATING THE EX- HAUSTION F GAS PURIFYING MASSES -'AND A METHOD OF USING THE SAME Oskar Neumann, Oranienburg, near Berlin, Germany, assignor to Deutsche Gasgluhlicht-Auer-'- Gescllschaft m. b. 11., Berlin, Germany, a corporation of Germany No Drawing.

Application September 21, 1929,

Serial No. 394,390, and in Germany November 4 Claims. (Cl. 2522.5)

With protective breathing apparatus it is absolutely necessary in many instances, where the poisonous substance proper such as carbon monoxide cannot be noticed, to provide a device.

warned in time, even if his attention. is diverted. Nitride of magnesium was found to be particularly serviceable for these purposes and the said substance possesses the above described advantages even when used in relatively small 5 Within the apparatus, which will indicate the quantities of about 20 grams and less. -The' solid 0 exhaustion of the purifying agent. products of decomposition of nitride of magne- Such exhaustion of the purifying matter is sium will in no way impair the normal opera-, governed in many, instances by, the moisture tion of the filter of the breathing apparatus. present in the gas mixture, as for instance with In addition the ammonia is generated in such a 10 purifying matter of a catalytic nature, such as concentration that it will not hurt the wearer 5 hopcalite, which causes combustion of carbon of the apparatus. Nitride of magnesium is parmonoxide. Water in the form of vapor has a ticularly adapted as warning substancein purideleterious action on hopcalite so that it is necfying masses, which removethe carbonic oxide essary to choose an indicator which is sensitive catalytically, such as the well known hopcalite to water vapor. which is a mixture of metal oxides such as man Up to the present there were introduced exganese dioxide, copper oxide, cobaltic oxide and clusively within the purifying matter such subsilver oxide. Usually a charge of about 310 stances, which possess a characteristic'smell'or grams or so of hopcalite is used in a breathing which will generate a substance havinga charapparatus. r

20 acteristic smell. It wasv found however, that in I claim: g many instances the person carrying the appa- 1. In a gas breathing apparatus, the combinratus got accustomed to such smell, so that duration of gas purifying matter and magnesium ing heavy work its occurrence was no longer nitride.

noticed. With calcium carbide, for instance, it 2. In a gas breathing apparatus, the combin- 25 is notpossible at all, to obtain by an increase of ation of gas purifying matter and magnesium the quantity of the warning substance in the nitride, the said magnesium nitride being prespurifying apparatus an increased annoyance rent in relatively small quantities while, being caof smell to the wearer of the said apparatus. pable-of generating, such quantities of ammonia For various reasons theapplicatio n of the quanthat willcaus'e a noticeable annoyance to the 30 tity of warning substance employed in breathing wearer of the breathing apparatus prior to the protective devices is' naturally limited through full exhaustion-of said gas purifying matter. the whole construction of the appliance. 3. The 'method of indicating the exhaustion Considerable progress has been made in the of gas purifying matter in a breathing apparatus, art by the present discovery of a substance cawhich comprises causing air passing through 35 pable of not only generating'in relatively small the breathing apparatus to come into contact quantities a warning medium indicating that the with magnesium nitride whereby ammonia will gas purifying matter in a breathing apparatus be generated when the gas purifying matter is or gas mask is becoming 'exhausted, but also approaching exhaustion.

capable of'increasing the concentration of the 4. In a gas breathing apparatus, gas purify- 40 warning medium, as-the purifying matter or filter, ing matter the exhaustion of which is governed becomes almost completely exhausted in such a by the moisture present in the gas beingbreathed, manner-thatthe irritationof the warning mein conjunction with magnesium nitride, to de- 7 dium upon the wearer of the breathing apparavelop'warning vapors of ammonia by the action tus will increase to a proper annoyance. of such moisture on said magnesium nitride 45 A further advantage of any warning medium, prior to the full exhaustion of said gas purifying which is nitride of magnesium, is that ammonia matter. is generated when the gas purifyingmatter is' OSKAR NEUMANN. becoming exhausted and that the smell of 'ammonia makes it possible for the wearer to notice 50 the approaching exhaustion of the gas purifying matter. On further exhaustion of said gas purifying matter the said smell of ammonia will ultimately be increased to such a noticeable an-" 55 noyance that the wearer of the apparatus is 

